The Exposure Core consists of an AinA/ay (Lung) Exposure Core based in Denver at National Jewish Health and a Skin Exposure Core based at University of Colorado Denver on the medical campus. The Ainway (Lung) Exposure Core consists of an offsite exposure facility at USAMRICD (Aberdeen, MD) subcontracted for exposure of rats to SM (described herein) supervised by our collaborator Dana Anderson, and Denver (National Jewish Health)-based exposure facilities for ain/vay exposures to half-mustard (2-chloroethyl ethylsulfide, CEES;nose-only system) and chlorine (whole body). The former provides an ethanolic aerosol (0.6 micron mass median diameter) by nose-only delivery to anesthetized rats in an established model. The latter provides chlorine gas in dry dilution air by whole body exposure to conscious rats in a more recently constructed system that is functioning and providing results similar to those reported by others with similar levels of exposure. Verification of exposure levels in the chlorine system is based on the 'sulfamic acid trap'method previously described Rando and colleagues. Processing of lung tissue and body fluids from rats exposed to these three toxic inhaled gases is illustrated in schematic diagram. For studies requiring airway instillation of drugs (eg tPA) with SM exposure, a small group of investigators (1) and technicians (2) from National Jewish will travel to USAMRICD 2-4 times annually to assist in these more labor-intensive studies. Pulmonary function testing (flexiVent) is available nearby to CEES and chlorine exposure systems in Denver, and also at the SM facility in Aberdeen (Buxco whole body plethysmography). The latter is described herein and the former is in Project 1. The Ainway Exposure Core is heavily used mainly by Projects 1 and 2. The Skin Exposure Core during the first cycle established an in vivo exposure system for CEES that can cause reproducible microvesication, DNA damage, inflammation and edema, and more recentiy has developed a nitrogen mustard exposure system that results in all of these events but with much more marked potency. The Core includes interactive studies will all 3 Projects.